Bengaluru's air has become significantly more toxic, according to a recent study. Air quality measured in the city over an eight-year period in six locations revealed that while sulphur dioxide levels had decreased, airborne particulate matter have either been 'high' or 'critical' in most areas.

The eight-year trend analysis between 2006 and 2013, showed that the overall percentage increase in airborne particulate matter was 216 per cent in KHB, 161.2 per cent in AMCO, 119.3 per cent in Victoria Hospital, 80.3 per cent at YPR, 76.5 per cent at Graphite India, and 17.5 per cent in Peenya.

MORE VEHICLES, MORE POLLUTIONThe main source of pollution in the city is the exponential growth in the number of vehicles . It contributes to almost 50 per cent of the pollution. The other contributors are construction activities, paved and unpaved road dust, domestic pollution and the increased use of diesel generator sets, said experts.

Anitha Chinnaswamy, lead researcher from Coventry University, UK, said in her findings: "All six areas have varying levels of PM10 (particulate matter 10 micrometres or less in diameter), with pollution classifications as mainly high or critical. Across all areas, the concentration level of PM10 in 2013 was critical. Overall, four air pollutants, namely sulphur dioxide, nitrogen oxide, suspended particulate matter and respirable suspended particulate matter (RSPM/PM10), were monitored at all locations."

"Based on data obtained from the Karnataka State Pollution Control Board (KSPCB) for eight years, the paper critically analysed the trend of pollutants identified by the six air quality monitoring stations managed by KSPCB, within their respective areas of coverage and, based on that analysis, alert both researchers and local authorities to the necessity of overcoming the limitations of insufficient monitoring," she said.

Her previous research project, taking Bengaluru as a case study, had for the first time established a link between deaths due to cardiovascular diseases and high levels of particulate matter that are 10 micrometres or less in diameter, referred to as 'PM10'.

"In general, particulate matter causes a wide range of diseases and its presence is said to be more dangerous to human health than any other common air pollutant," she added.

HEALTH RISKSThe current paper says that the three industrial areas varied in air quality classification from moderate to critical, with KHB industrial area generally having fluctuating levels of pollution.

In 2013, the level of PM10 in KHB was at its highest — an alarming 182 micrograms per cubic metre (g/m3) — across the eight years under consideration. (The World Health Organisation [WHO] safe limit for annual mean of PM10 levels is 20 g/m3. A WHO report earlier this year had showed that PM10 level for Bengaluru was 118 g/m3.)

The levels found at Graphite industrial area were also alarmingly high, revealed the analysis. The PM10 values of 194 g/m3 in 2007, and 184 g/m3 in 2009, were over three times above the acceptable limit.

The level in 2013 stood at 162 g/m3, which was 2.7 times the acceptable limit.

Victoria Hospital consistently maintained a high level of PM10 pollution, from 2006 to 2012. However, in 2013 this level shot up to 152 g/m3, three times that of the previous year and over 2.5 times the safe limit set by the Central Pollution Control Board (CPCB), the researchers observed.

"The same observation applies to the two residential areas of Yeshwanthpur (YPR) and AMCO, where there was a respective significant increase in concentration in 2013, in comparison with the seven previous years," said the multi-national research team.

"For Bengaluru, the critical levels of PM are likely to have a damaging effect on the health of the citizens that may result in a tremendous burden on the public health system. Additionally, if this were to affect the skilled young human resource, it would pose a threat to the city's economy. Therefore, it is of vital importance that the government addresses the issue of health impact due to air pollution by adhering to stringent measures of pollutants' control," the researchers said.

OTHER POLLUTANTSAccording to the researchers, the sources of sulphur dioxide, applicable to the city, are mainly due to the burning of fossil fuels and diesel exhaust, and the health effects attributable to it are known to be inflammation of the respiratory tract, lung damage, and irritation in the eyes, mucous membranes and the skin.

Their analysis showed that generally the levels of sulphur dioxide tended to decrease in these areas.

"Since fuel type and quality are one of the major contributors to sulphur dioxide, the overall decreasing trend may be attributed to various regulatory measures taken, such as the reduction of sulphur in diesel fuel and the wider use of liquefied petroleum gas (LPG), instead of coal, as domestic fuel," said Chinnaswamy.

The researchers analysed levels of nitrogen oxide, exposure to which, according to experts, is linked to adverse respiratory effects and airway inflammation in healthy people, and increased respiratory symptoms in people with asthma.

Assessment shows that in both YPR and AMCO residential areas, nitrogen oxide concentration levels over the year 2009 were at their highest, with a moderate air pollution classification.

However, over the subsequent years to 2013, there was a consistent decrease in nitrogen oxide pollution and, its concentration levels decreased by 24.4 per cent and 23.8 per cent in YPR and AMCO, respectively.

"Industrial areas of KHB, Graphite and Peenya saw similar peaks in its concentration levels in 2009 (except for Graphite, where the highest level of 50.7g/m3 was reached in 2006) before assuming a generally downward trend. In Victoria too, there was a similar pattern, with 2009 marking a peak value, followed by a downward trend," said the findings.

The researchers said a possible explanation for the universal increased nitrogen oxide concentration level in 2009 may be attributed to the increase in the number of cars. "Although the number of vehicles (whether registered or not) has been generally increasing in Bengaluru, the number of registered vehicles, particularly over 2007-09, saw an exponential increase of over half a million additional vehicles. As motor vehicle exhaust emissions are one of the major contributors to nitrogen oxide dispersion, this noticeable increase in vehicular traffic could have contributed to the significant increase in levels in 2009," they added.

“To save the environment and to fight climate change, my government has planned a major campaign. By 2022, we want to generate 175 GW of renewable energy. In the last three years, we have already achieved 60 GW or around one-third of this target,” he said.